1. Introduction to Computers1
Introduction to Computers

2. References
These slides mainly adopted from the Book’s slides by Pearson Education Inc., 2008.

3. OBJECTIVES In this chapter you’ll learn:
Basic hardware and software concepts.
Object-technology concepts, such as classes, objects, attributes, behaviors, encapsulation and inheritance.
The different types of programming languages.
A typical C++ program development environment.

4. 1.1 Introduction 1.2 What Is a Computer? 1.3 Computer Organization 1.4 Early Operating Systems 1.5 Personal, Distributed and Client/Server Computing 1.6 The Internet and the World Wide Web 1.7 Web Machine Languages, Assembly Languages and High-Level Languages 1.9 History of C and C C++ Standard Library 1.11 History of Java 1.12 Fortran, COBOL, Pascal and Ada 1.13 Basic, Visual Basic, Visual C++, C# and .NET 1.15 Typical C++ Development Environment

5. 1.1 Introduction Hardware Software Structured programming
Instructions to command computer to perform actions and make decisions
Structured programming
Object-oriented programming

6. 1.2 What Is a Computer? Computer Computer programs Hardware
Device capable of performing computations and making logical decisions
Computer programs
Sets of instructions that control computer’s processing of data
Written by people called computer programmers
Hardware
Various devices comprising computer
Keyboard, screen, mouse, disks, memory, CD-ROM, processing units, etc.

7. 1.3 Data Hierarchy

8. 1.4 Computer Organization
Six logical units of computer
Input unit
“Receiving” section
Obtains information from input devices
Keyboard, mouse, microphone, scanner, networks, etc.
Output unit
“Shipping” section
Places information processed by computer on output devices
Screen, printer, networks, etc.
Information can also be used to control other devices

9. 1.4 Computer Organization (Cont.)
Six logical units of computer (Cont.)
Memory unit
Rapid access, relatively low capacity “warehouse” section
Retains information from input unit
Immediately available for processing
Retains processed information
Until placed on output devices
Often called memory or primary memory
Arithmetic and logic unit (ALU)
“Manufacturing” section
Performs arithmetic calculations and logic decisions

10. 1.4 Computer Organization (Cont.)
Six logical units of computer (Cont.)
Central processing unit (CPU)
“Administrative” section
Coordinates and supervises other sections of computer
Secondary storage unit
Long-term, high-capacity “warehouse” section
Stores inactive programs or data
Secondary storage devices
Hard drives, CDs, DVDs
Slower to access than primary memory
Less expensive per unit than primary memory

11. A Brief History of Computing
1936: Z1 Computer (Konrad Zuse)
First freely programmable computer, electro-mechanical punch tape control.
1944: Mark I (IBM)
First universal calculator
The IBM Automatic Sequence Controlled Calculator (ASCC) Computer was created by IBM for Harvard University.

12. A Brief History of Computing
1946: ENIAC
ENIAC (Electronic Numerical Integrator And Computer).
the first general purpose (programmable to solve any problem) electric computer.
It weighed 27 tones and used 150 kW of power
1953: IBM 701 EDPM
IBM enters the market with its first large scale electronic computer.

13. A Brief History of Computing
1960: First commercial transistorized computers
DEC introduced the PDP-1 and IBM released the 7090 which was the fastest in the world.

14. 1964 – The mouse and window concept
A Brief History of Computing
Aug
1964 – The mouse and window concept
Douglas Engelbart shows the worlds first “mouse”
SRI (Stanford Research Institute) received a patent on the mouse in 1970, and licensed it to Apple for $40,000.

15. 1.5 Machine Languages, Assembly Languages and High-Level Languages
Three types of computer languages
Machine language
Only language computer directly understands
“Natural language” of computer
Defined by hardware design
Generally consist of strings of numbers
Ultimately 0s and 1s
Instruct computers to perform elementary operations
Cumbersome for humans
Example

16. Three types of computer languages (Cont.)
1.5 Machine Languages, Assembly Languages and High-Level Languages (Cont.)
Three types of computer languages (Cont.)
Assembly language
English-like abbreviations representing elementary computer operations
Clearer to humans
Incomprehensible to computers
Convert to machine language by translator programs (assemblers)
Example
load basepay add overpay store grosspay

17. 1.5 Machine Languages, Assembly Languages and High-Level Languages (Cont.)
Three types of computer languages (Cont.)
High-level languages
Similar to everyday English
Uses common mathematical notations
Single statements accomplish substantial tasks
Converted to machine language by translator programs (compilers)
Interpreter programs
Directly execute high-level language programs
Execute more slowly than the compiled program
Example
grossPay = basePay + overTimePay

18. 1.7 Operating Systems Early computers Operating systems (OS)
Single-user batch processing
Only one job or task at a time
Process data in groups (batches)
using punched cards
Users had to wait hours or days for results
Operating systems (OS)
Software systems that manage transitions between jobs
Increased throughput
Amount of work computers can process

19. 1.7 Operating Systems (Cont.)
Multiprogramming
Many jobs or tasks sharing computer’s resources
“Simultaneous” operation of many jobs
Timesharing
Special case of multiprogramming
Users access computer through terminals
Devices with keyboards and screens
Dozens, even hundreds of users
Computer use is shared among all users
Performs small portion of one user’s job, then moves on to service next user
Advantage
User receives almost immediate responses to requests

20. 1.7 Operating Systems (Cont.)
Windows—A Proprietary Operating System
In the mid-1980s, Microsoft developed the Windows OS, a graphical user interface built on top of DOS
Linux—An Open-Source Operating System
First release on 1991
Open-source software is a software development style that dominated software’s early years.
Linux distributions: Red Hat, Ubuntu, ….
extremely popular on servers and in embedded systems (e.g. Google’s Android-based smartphones)

21. 1.8 Programming Languages
Fortran: (FORmula TRANslator) by IBM
COBOL: (Common Business Oriented Language) late1950s
Pascal: 1960s
Ada: based on Pascal (by the US DoD)
Basic: 1960s
C: 1972
Objective-C
Java: 1991
Visual Basic: 1990s
Visual C#: 2001 by Microsoft
Object-oriented, “scripting” languages for web programming:
PHP: open-source (Wikipedia & Facebook)
Perl: (Practical Extraction and Report Language) 1987,
Python: 1991
JavaScript: the most widely used scripting language
Ruby on Rails
Scala: 2003, uses both the object-oriented and functional programming paradigms (Tweeter)

22. 1.9 C and C++ History of C Evolved from BCPL and B
Developed by Dennis Ritchie (Bell Laboratories)
Development language of UNIX
Hardware independent
Can write portable programs
ANSI and ISO standard for C published in 1990
ANSI/ISO 9899: 1990

23. Portability Tip 1.1
Because C is a standardized, hardware-independent, widely available language, applications written in C often can be run with little or no modification on a wide range of computer systems.

24. 1.9 C and C++ (Cont.) History of C++ Extension of C
Developed by Bjarne Stroustrup (Bell Laboratories) in early 1980s
Provides new features to “spruce up” C
Provides capabilities for object-oriented programming
Objects: reusable software components
Model items in the real world
Object-oriented programs
Easier to understand, correct and modify

25. 1.10 C++ Standard Library C++ programs C++ Standard Library
Built from pieces called classes and functions
C++ Standard Library
Rich collections of existing classes and functions
Reusable in new applications

26. Software Engineering Observation 1.1
Use a “building-block” approach to create programs. Avoid reinventing the wheel. Use existing pieces wherever possible. Called software reuse, this practice is central to object-oriented programming.

27. Software Engineering Observation 1.2
When programming in C++, you typically will use the following building blocks: Classes and functions from the C++ Standard Library, classes and functions you and your colleagues create, and classes and functions from various popular third-party libraries.

28. Performance Tip 1.1
Using C++ Standard Library functions and classes instead of writing your own versions can improve program performance, because they are written carefully to perform efficiently. This technique also shortens program development time.

29. Portability Tip 1.2
Using C++ Standard Library functions and classes instead of writing your own improves program portability, because they are included in every C++ implementation.

30. Software Engineering Observation 1.3
Extensive class libraries of reusable software components are available over the Internet. Many of these libraries are free.

31. 1.9 Typical C++ Development Environment
C++ programs normally undergo six phases
Edit
Programmer writes program (and stores source code on disk)
Preprocess
Perform certain manipulations before compilation
Compile
Compiler translates C++ programs into machine languages
Link
Link object code with missing functions and data
Load
Transfer executable image to memory
Execute
Execute the program one instruction at a time

32. Fig. 1.1 | Typical C++ environment.

33. 1.9 Typical C++ Development Environment (Cont.)
Input/output
cin
Standard input stream
Normally inputs from keyboard
cout
Standard output stream
Normally outputs to computer screen
cerr
Standard error stream
Displays error messages

34. Common Programming Error 1.1
Errors such as division by zero occur as a program runs, so they are called runtime errors or execution-time errors. Fatal runtime errors cause programs to terminate immediately without having successfully performed their jobs. Nonfatal runtime errors allow programs to run to completion, often producing incorrect results.
[Note: On some systems, divide-by-zero is not a fatal error. Please see your system documentation.]